University of Ottawa Heart Institute.
School of Epidemiology and Public Health, University of Ottawa.
Can J Neurol Sci. 2022 Mar;49(2):218-224. doi: 10.1017/cjn.2021.62. Epub 2021 Apr 12.
Several guidelines currently recommend acute diffusion weighted imaging (DWI) for the detection of ischemia in transient ischemic attack (TIA). However, DWI hyperintensities resolve early and only 30%-50% with clinically defined TIA show acute DWI positivity. A recent meta-analysis reported an unexplained 7-fold variation in DWI positivity in TIA across studies, concluding that DWI does not provide a consistent basis for defining ischemia. Intracortical excitability, measured using transcranial magnetic stimulation (TMS), has previously been shown to be altered after TIA and associated with ABCD2 scores; however, whether altered cortical excitability is associated with clinical and DWI-based definitions of TIA remains unclear.
Individuals with TIA symptoms (N = 23; mean age = 61 ± 12) were prospectively recruited and underwent DWI and paired-pulse TMS. Multivariate linear regression was used to estimate associations between TMS-derived excitability thresholds, and clinical TIA diagnosis, and imaging-based evidence of cerebral ischemia (DWI positivity). Area under the curve (AUC) analyses was used to compare the discriminability of TMS-derived thresholds and clinical TIA diagnoses.
Thresholds for intracortical inhibition in the TIA-unaffected hemisphere were significantly associated with the clinical diagnosis of TIA. No associations between TMS-derived thresholds and DWI positivity were observed. TMS thresholds showed low-moderate discriminability and values differed by age (65+) and sex.
In this small sample, TMS-derived markers of intracortical excitability were associated with clinical TIA diagnoses but not DWI positivity. Our results provide preliminary evidence for the potential discriminative utility of TMS for the diagnosis of TIA and highlight the need for future work in larger cohorts.
目前有几项指南建议对短暂性脑缺血发作（TIA）使用急性弥散加权成像（DWI）检测缺血。然而，DWI 高信号在早期就会消退，只有 30%-50%具有临床定义的 TIA 表现出急性 DWI 阳性。最近的一项荟萃分析报告称，在不同研究中 TIA 的 DWI 阳性率存在无法解释的 7 倍差异，结论是 DWI 并不能为定义缺血提供一致的基础。先前的研究表明，经颅磁刺激（TMS）测量的皮质内兴奋性在 TIA 后发生改变，并且与 ABCD2 评分相关；然而，皮质兴奋性的改变是否与 TIA 的临床和基于 DWI 的定义相关仍不清楚。
前瞻性招募了 23 名 TIA 症状患者（平均年龄=61±12），并进行了 DWI 和成对脉冲 TMS 检查。多元线性回归用于估计 TMS 衍生兴奋性阈值与临床 TIA 诊断和基于影像的脑缺血证据（DWI 阳性）之间的相关性。曲线下面积（AUC）分析用于比较 TMS 衍生阈值和临床 TIA 诊断的鉴别能力。
TIA 未受影响半球的皮质内抑制阈值与 TIA 的临床诊断显著相关。未观察到 TMS 衍生阈值与 DWI 阳性之间的相关性。TMS 阈值的鉴别能力为低到中等，并且值因年龄（65+）和性别而异。
在这个小样本中，TMS 衍生的皮质内兴奋性标志物与临床 TIA 诊断相关，但与 DWI 阳性无关。我们的研究结果初步证明了 TMS 在 TIA 诊断中的潜在鉴别效用，并强调了在更大队列中进行未来研究的必要性。
